Michael Hoey fired his third successive 66 to take a three-shot lead into the final round of the Alfred Dunhill Links Championship.
On a leaderboard dominated by players from Northern Ireland, Hoey's closest rival is 2010 US Open Champion Graeme McDowell, who collected his third score of 67 at a cool and damp St Andrews.
Hoey moved to 18 under par by taming Carnoustie, the toughest of the three courses staging this event.
Competitors playing their third rounds at Kingsbarns suffered an hour-long delay as a consequence of late morning fog but the view was much clearer further north at Carnoustie, where Hoey had an eagle, five birdies and just one dropped shot in a round that began by playing the back nine first.
The 32-year-old former Amateur Champion birdied the 11th and 12th holes before collecting an eagle three at the long 14th.
After the turn he collected three birdies in four holes including a holed bunker shot at the third - and it is no surprise to McDowell that Hoey is setting the pace.
"We played a lot of amateur golf together on Irish and Ulster teams and he's always been a very talented ball striker," said McDowell.
"He's the kind of guy who when he puts it all together and gets his head right will win and win well, and impress you as much as any of the top players in the world.
"When he was 18, 19, 20, you really thought he was going to kick on and become a world beater, why he hasn't done that - who knows?"
Hoey claimed his second European Tour title when he won the Madeira Islands Open in May this year but has not registered a finish in the top 30 since. He will play with McDowell in the final round.
South Africa's Louis Oosthuizen lies third, four shots off the pace after carding a three-under-par 69 in his first competitive round on the Old Course since his 2010 Open victory at St Andrews.
World number one Luke Donald and Simon Dyson both equalled the course record at St Andrews, set by Rory McIlroy at last year's Open, with their rounds of 63.
"I'm very, very happy with the day," said Dyson, who is 30th in the world rankings after two wins this year.
"I didn't realise my birdie putt on the 18th was for the course record otherwise I might have hit it a bit harder. But it's a good name to share the record with."
Donald credited a good night's sleep as the key to his round, while Dyson put his fine form down his current abstinence from alcohol.
Dyson is steering clear of alcohol during his wife's pregnancy, although the recent Irish and Dutch Open champion says he is likely to break his pledge if he goes on to win his second Links Championship title on Sunday.
The Englishman is in a logjam of players sharing fourth place at 13 under par, along with Donald and young Scot George Murray, who went round Kingsbarns in 67.
McIlroy is also at 13 under, and after his third round of 66 at St Andrews revealed he has been taking a miniature sand wedge on his travels to help groove his swing. He uses the cut-down club to rehearse swings while in front of the mirror in his hotel rooms.
Tommy Fleetwood, who shared the halfway lead, struggled to a 71 at Carnoustie that leaves him in the group sharing fourth place. Padraig Harrington, twice a Links champion, fired a 64 at St Andrews and he is also within five shots of Hoey's lead.